Internal combustion engine ignition spark vacuum advance mechanism delay system



NOV. 4, 1969 ucms ET AL 3,476,094

INTERNAL COMBUSTION ENGINE IGNITION SPARK VACUUM ADVANCE MECHANISM DELAY SYSTEM Filed March 13, 1968 TO A PORT ON THE ENGINE INTAKE MANIFOLD INVENTORS Y B igffz ficizzs 5 Y o e I aemse ATTORNEY United States Patent 3,476,094 INTERNAL COMBUSTION ENGINE IGNITION SPARK VACUUM ADVANCE MECHANISM DELAY SYSTEM Erik H. Rucins, Utica, and Robert W. Guernsey, Rochester, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Mar. 13, 1968, Ser. No. 712,649 Int. Cl. F021 5/10 US. Cl. 123-117 3 Claims ABSTRACT OF THE DISCLOSURE A system for delaying the operation of the ignition spark vacuum advance mechanism of an internal combustion engine in response to a rapid decrease of intake manifold vacuum from any stabilized value. Both sides of the diaphragm of a double acting valve actuator vacuum unit are exposed to the engine intake manifold vacuum through a vacuum line which is divided into two branches, one of which includes an orifice. With conditions of stabilized manifold vacuum, the pressure across the diaphragm is equalized to operate a valve to a first position which provides an open passage therethrough between the spark advance vacuum unit and carburetor spark advance ports. A sudden decrease of manifold vacuum will result in a pressure differential across the diaphragm because of the orifice, consequently, the diaphragm moves in the direction toward the lowest pressure to operate the valve from the first position to a second position which vents the spark advance vacuum unit to atmosphere until the pressure across the diaphragm again equalizes.

This invention relates to internal combustion engine ignition spark vacuum advance mechanisms and, more specifically, to a system for delaying the operation of the ignition spark vacuum advance mechanism in response to a rapid decrease of intake manifold vacuum from any stabilized value.

The ignition spark of most internal combustion engines, particularly those with automotive applications, is retarded during idling and slow engine speed conditions and advanced during conditions of acceleration and cruising or substantially constant engine speeds. One mechanism which operates to advance the ignition spark in response to engine vacuum during acceleration and to maintain the spark advance with constant engine speeds includes a movable distributor breaker plate, upon which the ignition breaker contacts are mounted, which is revolved by a spark advance unit having a spark advance port connected through a vacuum line to a spark advance port of the carburetor. With the throttle plate closed, the carburetor spark advance port is open to substantially atmospheric pressure and the spark advance vacuum unit positions the movable breaker plate to provide a retarded spark. As the throttle plate is opened, the carburetor spark advance port and, consequently, the spark advance vacuum unit spark advance port become exposed to intake manifold vacuum which activates the spark advance vacuum unit to revolve the movable breaker plate in the direction to advance the ignition spark. With a constant throttle opening, such as at crusing speeds in an automobile, the manifold vacuum stabilizes, consequently, the spark advance vacuum unit maintains the degree 'of ignition spark advance substantially constant.

With certain operating conditions, it may be desirable to delay the operation of the ignition spark vacuum advance mechanism during periods of acceleration until the acceleration has been completed.

It is, therefore, an object of this invention to provide an improved internal combustion engine ignition spark vacuum advance mechanism delay system.

It is another object of this invention to provide an improved internal combustion engine ignition spark vacuum advance mechanism delay system which is responsive to a rapid decrease of intake manifold vacuum from any stabilized value.

In accordance with this invention, a system for delaying the operation of the ignition spark vacuum advance mechanism of an internal combustion engine in response to a rapid decrease of intake manifold vacuum from any stabilized value is provided wherein a two way valve included in the vacuum line extending between the spark advance vacuum unit and carburetor spark advance ports is operated to a first position to provide an open passage between the spark advance ports during conditions of substantially constant engine speed and to vent the spark advance vacuum unit spark advance port to atmosphere during conditions of acceleration by a double acting diaphragm having opposite sides thereof connected to intake manifold vacuum through a first unrestricted vacuum line and a second restricted vacuum line.

For a better understanding of the present invention, together with additional objects, advantages and features thereof, reference is made to the following description and accompanying single figure drawing which sets forth the internal combustion engine ignition spark vacuum advance mechanism delay system of this invention.

The system of this invention operates in combination with a conventional carburetor 10 and distributor 12 and a ported intake manifold to delay the operation of the ignition spark vacuum advance mechanism in response to a rapid decrease of intake manifold pressure from any stabilized value. In the interest of reducing drawing complexity, the ported intake manifold is not shown in the figure as this is a common expedient well known in the automotive art.

Carburetor 10 may be of conventional design having a spark advance port 14- which opens into the carburetor mixing conduit 16 just above the throttle plate 17. At idle or conditions of very low engine speed, throttle plate 17 is closed or nearly closed, consequently, carburetor spark advance port 14 is exposed to substantially atmospheric pressure, as is shown in the figure. As the throttle plate 17 is revolved to open in a counterclockwise direction, as viewing the figure, carburetor spark advance port 14- becomes exposed to the engine intake manifold vacuum.

Distributor 12 may be of conventional design having an ignition spark advance mechanism of conventional design operated by a spark advance vacuum unit 18 having a spark advance port 19. As ignition spark vacuum advance mechanisms of this type are well known in the art and, per se, form no part of this invention, it has not been shown in detail in the figure. The operation will be explained in greater detail later in this specification.

Extending between the spark advance vacuum unit 18 and carburetor 1t spark advance ports 19 and 14, respectively, is a first vacuum line which includes vacuum line segments 20 and 21 and a two-way valve 22, having an operating member which may be a rod 23, which is operable to a first position to establish a vacuum connection between respective spark advance ports 19 and 14 and to a second position to vent the spark advance vacuum unit spark advance port 19 to atmosphere. Two-way valve 22 is illustrated in the figure as having a center chamber 24 and two outside chambers 25 and 26 separated by respective walls 27 and 23. Each of chambers 24, 25 and 26 communicates externally of valve 22 through respective ports 29, 30 and 31. Internally of valve 22, center cham ber 24 communicates with outside chamber 25 through an inside port 32 having an angularly disposed valve seat 33 while center chamber 24 communicates with the other outside chamber 26 through an inside port 34 having an angularly disposed valve seat 35. Port 29 of two-way valve 22 is interconnected with the spark advance vacuum unit spark advance port 19 through vacuum line segment 20, port 30 is interconnected with the carburetor spark advance port 14 through vacuum line segment 21 and port 31 is vented to the atmosphere. Secured to the end of operating member 23 within valve 22 is a piston 36 having two angularly disposed faces 37 and 38 which are arranged to engage respective angularly disposed valve seats 33 and 35 in a tight complementary fit. To operate valve 22 to the first and second positions, operating member 23 may be moved linearly, In the first position of valve 22, face 37 of piston 36 is in a tight complementary fit with valve seat 33 to provide an open passage therethrough between only ports 29 and 30 and in the second position, face 38 of piston 36 is in a tight complementary fit with valve seat 35 to provide an open passage therethrough between only ports 29 and 31. It is to be specifically understood that two-way valve 22 of the figure is only one example of many two-way valves which may be employed for this application.

To operate two-way valve 22, a double acting valve actuator vacuum unit 40 is provided. This unit includes a diaphragm 41 which is operated in a first direction by spring 42, downwardly as viewing the figure, and pressure differential operated against spring 42 in a second direction, upwardly as viewing the figure, an operating rod 43 connected to diaphragm 41 and linearly movable therewith in first and second directions and ports 44 and 45 located on respective opposite sides of diaphragm 41.

A vacuum line extends between the intake manifold port and, through a first branch 51 connected to port 45 of valve actuator vacuum unit 40 and a second branch 52 including a restriction 53 which may be an orifice connected to port 44 of valve actuator vacuum unit 40, to respective opposite sides of diaphragm 41. The intake manifold vacuum may, of course, be applied to respective opposite sides of diaphragm 41 through separate respective vacuum lines.

A sudden decrease in manifold vacuum upon a sudden opening of the throttle valve 17 will result in a pressure differential across diaphragm 41 of valve actuator vacuum unit 40 of a greater magnitude on the side of port 45, which operates diaphragm 41 against the bias of spring 42 in the second direction, because the fiow of air to the opposite side of diaphragm 41 through port 44 will be impeded by restriction or orifice 53.

An operating linkage is provided between diaphragm 41 of valve actuator vacuum unit 40 and two-way valve 22 for operating valve 22 to the first position with diaphragm 41 operated in the first direction and to the second position when diaphragm 41 is operated in the second direction. This linkage may include operating rod 43, connected to diaphragm 41 of valve actuator vacuum unit 40, interconnected with operating member 23 of two-way valve 22 by a conventional coupling 54 in such a manner that valve 22 is operated by valve actuator vacuum unit 40 to the first position with diaphragm 41 operated in the first direction and to the second position when diaphragm 41 is operated in the second direction with sudden decreases of engine manifold vacuum.

With conventional ignition spark vacuum advance mechanisms, the carburetor spark advance port is directly interconnected, through a vacuum line, with the spark advance vacuum unit spark advance port. The spark advance vacuum unit may be a vacuum motor very similar to that illustrated for double acting valve actuator vacuum unit 40 with the port corresponding to port 45 vented to the atmosphere. Mounted within the distributor is a movable breaker plate, upon which the ignition breaker contact points are mounted, which is rotatable in a plane normal to the axis of the distributor drive shaft to advance and retard the engine ignition spark. This movable breaker plate is revolved by an operating arm, such as that referenced by the numeral 60 of the figure, which is attached to and linearly moved by the diaphragm within the spark advance vacuum unit. At idle or conditions of low engine speed with the carburetor throttle plate closed or nearly closed, the carburetor spark advance port is exposed to atmospheric pressures, consequently, the diaphragm of the spark advance vacuum unit is exposed to atmosphere on both sides. Under these conditions, the diaphragm and connected operating rod are forced by a spring in the direction which will rotate the movable breaker plate within the distributor in the direction which will retard the ignition spark. With the carburetor throttle plate opened during acceleration or cruising speeds, the carburetor spark advance port is exposed to engine intake manifold vacuum, consequently, the diaphragm of the spark advance vacuum unit is exposed to manifold vacuum on the side of the spark advance port. Under these conditions, the diaphragm within the spark advance vacuum unit and connected operating rod are forced in the opposite direction by the greater pressure on the side of the port vented to the atmosphere to rotate the movable breaker plate in the direction which will advance the ignition spark.

With the engine intake manifold vacuum stabilized, spring 42 of valve actuator vacuum unit 40 operates diaphragm 41 in the first direction to omrate two-way valve 22 to the first position which provides an open passage therethrough between only ports 29 and 30. Consequently, a vacuum line connection is established between respective spark advance ports 19 and 14 of spark advance vacuum unit 18 and carburetor 10 and the ignition spark vacuum advance mechanism operates in the conventional manner.

Upon a sudden acceleration or decrease in manifold vacuum, diaphragm 41 of valve actuator vacuum unit 40 is pressure differential operated in the second direction to operate two-way valve 22 to the second position which provides an open passage therethrough between only ports 29 and 31 to vent the spark advance vacuum unit spark advance port 19 to atmosphere. Therefore, even though spark advance port 14 of carburetor 10 is exposed to engine intake manfold vacuum, a condition which would normally result in a spark advance with a conventional spark advance mechanism, the operation of spark advance vacuum unit 18 is delayed as atmospheric pressure is present upon spark advance port 19 thereof and the same degree or substantially the same degree of spark retard as under idle or low speed conditions is maintained.

When the engine intake manifold vacuum becomes stabilized, the pressure across diaphragm 41 of valve actuator vacuum unit 40 equalizes and diaphragm 41 moves in the second direction under the influence of spring 42 to operate two-way valve 22 to the first position which establishes a vacuum connection between the spark advance vacuum unit 18 and carburetor 10 spark advance ports 19 and 14, respectively. As the throttle plate 17 is now open, the intake manifold vacuum acting through this vacuum line connection operates spark advance vacuum unit 18 in a direction to advance the engine ignition spark after a delay period as determined by the length of time required to stabilize intake manifold vacuum.

Some engines are equipped with a mechanism which provides an extra spark retard. This equipment may be a double ported carburetor having a spark retard port below the throttle plate and on the opposite side of the mixing conduit from the spark advance port which is interconnected with a spark retard port on the spark advance vacuum unit or by a centrifugal mechanism which provides a greater retard at idle speeds. It is to be specifically understood that the system of this invention may be utilized with either of these systems.

What is claimed is:

1. An internal combustion engine ignition spark vacuum advance mechanism delay system comprising in combination with a carburetor having a spark advance port, a distributor having an ignition spark advance mechanism operated by a spark advance vacuum unit having a spark advance port and a ported intake manifold; a first vacuum line extending between said spark advance vacuum unit and carburetor spark advance ports, a twoway valve included in said first vacuum line which is operable to a first position to establish a vacuum connection between said spark advance ports and to a second position to vent said spark advance unit spark advance port to atmosphere; a double acting valve actuator vacuum unit having a diaphragm spring operated in a first direction and pressure difierential operated against said spring in a second direction, a second vacuum line and a third restricted vacuum line extending between said intake manifold port and respective opposite sides of said diaphragm whereby a sudden decrease in engine manifold vacuum will result in a pressure differential across said diaphragm and an operating linkage between said diaphragm and said valve for operating said valve to the first position with said diaphragm operated in the first direction and to the second position when said diaphragm is operated in the second direction.

2. An internal combustion engine ignition spark vacuum advance mechanism delay system comprising in combination with a carburetor having a spark advance port, a distributor having an ignition spark advance mechanism operated by a spar-k advance vacuum unit having a spark advance port and a ported intake manifold; a first vacuum line extending between said spark advance vacuum unit and carburetor spark advance ports, a valve having an operating member included in said first vacuum line which is operable to a first position to complete an open passage between said spark advance ports and to a second position to vent said spark advance vacuum unit spark advance port to atmosphere; a double acting valve actuator vacuum unit having a diaphragm spring operated in a first direction and an operating rod connected to said diaphragm and linearly movable therewith in first and second directions, a second vacuum line extending between said intake manifold port and, through a first branch and a second branch having an orifice, to respective opposite sides of said diaphragm whereby a sudden decrease in engine manifold vacuum will result in a pressure differential across said diaphragm which operates said diaphragm against said spring in a second direction and means for connecting said operating rod of said valve actuator vacuum unit to said operating member of said valve in such a manner that said valve is operated to the first position with said diaphragm operated in the first direction to provide an open passage between said spark advance vacuum unit and carburetor spark advance ports and to the second position when said diaphragm is operated in the second direction to vent said spark advance port of said spark advance vacuum unit to atmosphere.

3. An internal combustion engine ignition spark vacuum advance mechanism delay system comprising in combination with a carburetor having a spark advance port, a distributor having an ignition spark advance mechanism operated by a spark advance vacuum unit having a spark advance port and a ported intake manifold; a valve having a first port interconnected with said spark advance vacuum unit spark advance port through a vacuum line, a second port interconnected with said carburetor spark advance port through a vacuum line and a third port vented to the atmosphere and an operating member which is operable to operate said valve to a first position to provide an open passage between only said first and second ports and to a second position to provide an open passage between only said first and third ports; a double acting valve actuator vacuum unit having at least first and second ports located on respective opposite sides of a diaphragm spring operated in a first direction and an operating rod connected to said diaphragm and linearly movable therewith in first and second directions; a vacuum line extending between said engine intake manifold port and through a first branch connected to said first port of said valve actuator vacuum unit and a second branch including an orifice connected to said second port of said valve actuator vacuum unit to respective opposite sides of said diaphragm whereby a sudden decrease in engine manifold vacuum will result in a pressure differential across said diaphragm of a greater magnitude on the side of said first port which operates said diaphragm against said spring bias in a second direction and means for connecting said operating rod of said valve actuator vacuum unit to said operating member of said valve in such a manner that said valve is operated by said valve actuator vacuum unit to the first position with said diaphragm operated in the first direction to provide an open passage between said spark advance vacuum unit and carburetor spark advance ports and to the second position when said diaphragm is operated in the second direction with sudden decreases of engine manifold vacuum to vent said spark advance port of said spark advance vacuum unit to atmosphere.

References Cited UNITED STATES PATENTS 2,380,967 8/1945 Jarvis 123l17.1 3,157,168 11/1964 Sterner et al 1231 17.1 3,356,083 12/1967 Clark et al. 1231l7.1 3,400,698 9/1968 Kelly 123117.1

C. J. HUSAR, Primary Examiner 

